1. Field of the Invention
This invention generally relates to integrated circuit (IC) fabrication and, more particularly, to patterned iridium oxide nanostructures and an associated fabrication process.
2. Description of the Related Art
Recently, the fabrication of nanostructures has been explored, due to its potential importance as a building block in nano, microelectromechanical (MEM), and nanoelectromechanical NEM device applications. For example, researchers associated with Charles Lieber have reported the synthesis of a variety of semiconductor nanowires made from materials such as silicon (Si), Si-germanium (SiGe), InP, and GaN, and use in building nano-computing system. Other groups have reported using templates structures to grow metallic nanowires made of materials such as Ni, NiSi, Au, and Pt. Metallic nanowires can be used as interconnections and the sharp tips of the nanowire make them effective for field emission purpose. ZnO2 nanowires are potentially useful as a light emission element.
IrO2 is a conductive metal oxide that is already widely used in DRAM and FeRAM applications. IrO2 can be used as a conductive electrode, as it has stable electrical and chemical properties, even at high temperature O2 ambient conditions. IrO2 can also be used as pH sensor material. Ir thin film can be deposited using PVD easily with excellent polycrystalline structure and strong (111) orientation. IrO2 can be formed afterwards, by oxidizing the Ir film, or it can be formed directly using reactive sputtering method at higher temperatures in oxygen ambient. CVD methods have recently been developed to grow Ir and IrO2 thin films. It is relatively easy to maintain good composition control in CVD processes, and the method is know to provide good step coverage on some materials.
No processes had been previously reported that are able to form metallic nanowires without the use of porous material forms or templates. The templates add a considerable degree of complexity to the process. Thus, a more practical and commercially feasible means of forming metallic nanowires publications is desirable. To that end, the above-mentioned Related Applications describe the growth of iridium oxide (IrO2) nanostructures formed using a metalorganic chemical vapor deposition (MOCVD) method without a template. The Related Applications describe an efficient MOCVD process for forming nanotips and nanorods. Using these MOCVD processes, IrO2 has been successfully grown on Ti, TiN, TaN and SiO2 substrates. The growth length, density, and vertical orientation can be controlled by temperature, pressure, flow, substrates, and time.
It would be advantageous if iridium oxide nanostructures, however formed, could be selectively formed or patterned on a substrate.
It would be advantageous if iridium oxide nanostructures could be selectively formed on a substrate, taking advantage of the differences in characteristics of adjoining substrate materials.
It would be advantageous if iridium oxide nanostructures could be selectively formed on a substrate, taking advantage of the differences in the manner in which iridium oxide covers adjoining substrate materials.